Noticeable, troublesome and objectionable limits of blur
| Autor: | Carol A. Pedersen, David A. Atchison, P. Gareth Ridall, Scott Warren Fisher |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Adult
Visual acuity Adolescent Letter size Visual Acuity Defocus Models Biological Pupil Optics medicine Humans Mathematics High contrast business.industry Vision Tests Pupil size Blur limits Middle Aged Sensory Systems Ophthalmology Sensory Thresholds medicine.symptom business Photic Stimulation Optometry |
| Zdroj: | Vision Research. 45(15):1967-1974 |
| ISSN: | 0042-6989 |
| DOI: | 10.1016/j.visres.2005.01.022 |
| Popis: | We investigated limits at which induced blur becomes noticeable, troublesome and objectionable. We used 15 cyclopleged subjects, a Badal optometer with lines of three high contrast letters as targets, 3–6 mm artificial pupils, and 0.0–0.7 logMAR letter sizes. For 0.0 logMAR size, mean ‘‘noticeable’’ blur limits were ±0.33D, ±0.30D and ±0.28D at 3 mm, 4 mm and 6 mm, respectively, but increased by about 70% for 0.7 logMAR letters. All limits reduced by about 17% as pupil size increased from 3 mm to 6 mm. Letter size had a significant influence on all blur limits (1.6–2.1 times), but blur direction had no significant effect. Magnitudes of ‘‘troublesome’’ and objectionable’’ limits were 1.6–1.8 times and 2.1–2.5 times relative to ‘‘noticeable’’ limits, respectively. Our results suggest criteria for troublesome and objectionable blur are relatively unaffected by letter size. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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